For example, in a component mounting apparatus which mounts electronic components on a circuit substrate, it is generally carried out to image a mark which was disposed on the circuit substrate and to recognized this, for the purpose of position detection etc. of the circuit substrate. In case of carrying out recognition of a mark on the suchlike circuit substrate, an image of the mark and its vicinity is picked up by a camera which was disposed on a mounting head, and that image is processed, and thereby, recognition of the mark is carried out. Then, on the occasion of picking up an image by the camera, an illumination apparatus for illuminating the mark and its vicinity is used. Examples of this kind of a recognition apparatus have been known in JP-A-9-116297 publication and JP-A-11-249020 publication etc.
FIG. 12 is a sectional side view which shows a first example of a recognition apparatus which is described in JP-A-9-116297 publication. This recognition apparatus is such a thing that illumination is carried out by an illumination apparatus 70, and an image is picked up by an image pickup camera 75, and the picked-up image which was obtained is processed by a control section 86, and thereby, a recognition operation of a mark etc. is carried out. The illumination apparatus 70 has a tube type case 71 whose lower surface was opened. At a center portion of a ceiling wall 72 of the case 71, a through-hole 73 is opened, and on the upper side of that through-hole 73, the image pickup camera 75 is disposed through a lens 74. An optic axis of the image pickup camera 73 runs through a center of the through-hole 73. In addition, at a lower position of the through-hole 73 in the case 1, disposed is a half mirror 76 which reflects illumination light to be hereinafter described, which is incident horizontally, toward a vertical-lower side, and transmits light which passes through the through-hole 73 from the vertical-lower side and is incident to the image pickup camera 75.
At a middle stand of an inside of the case 71 on the under side of the half mirror 76, a fixing plate 78 with a through-hole 77, which is coaxial with the through-hole 73, is disposed in such a form that it divides off an inside of the case 71 up and down. On a lower surface of that fixing plate 78, a number of first light sources 79 such as LEDs are disposed annularly, so as to surround and enclose the through-hole 77 at a center of the fixing plate 78. In addition, on a lower end face of the case 71, disposed is a diffusion plate which transmits illumination light from the first light source 79, which was disposed on the fixing plate 78, to a lower side, over diffusing it. At a center of this diffusion plate 80, disposed is a trough-hole 81 which is coaxial with each through-hole 77, 72, which was disposed on the fixing plate 78 and the ceiling wall 72 of the case 71, respectively.
In addition, in a peripheral wall 82 of the case 71, an opening 83 is formed. On an outside of that opening 83, disposed is a second light source 85 such as LED which makes illumination light incident horizontally toward the half mirror 76 in the case 71, through a lens 84. Then, the image pickup camera 75 picks up an image of an object 10 to be detected, which is in such a state that it was illuminated by the illumination apparatus 70, through each through-hole 81. 77, 73 of the diffusion plate 80, the fixing plate 78 and the ceiling wall 72 of the case 71. It is configured that a control section 86 processes this image obtained, to recognize the object 10 to be detected.
In case that an image of the object 10 to be detected is picked up by the image pickup camera 75, which was equipped with the suchlike illumination apparatus 70, to recognize it, the illumination apparatus 70 and the image pickup camera 75 are located on the upper side of the object 1 0 to be detected, and the first light source 79 and the second light source 79 are turned on, and thereby, over illuminating the object 10 to be detected and its vicinity, its image is picked up. In case that it was done, light 88, which was irradiated from the first light source 79, illuminates the object 10 to be detected and its vicinity, widely from periphery, over being diffused by the diffusion plate 80. In addition, light 89, which was irradiated horizontally from the second light source 85 through the lens 84, after it was reflected by the half mirror 76 in the case 71, passes through each through-hole 77, 81 of the fixing plate 78 and the diffusion plate 80, and illuminates the object 10 to be detected and its vicinity, from right above, with a directional characteristic. Therefore, the object 10 to be detected and its vicinity are illuminated by the light from right above and the light from periphery, and thereby, reflected light from the object 10 to be detected and its vicinity passes through each through-hole 81, 77, 73, and is incident to the image pickup camera 75. Thereby, an image of the object 10 to be detected and its vicinity is obtained.
FIG. 13 is a sectional side view which shows a second example of a conventional recognition apparatus which was described in the above-described JP-A-11-249020 publication. In an illumination apparatus 90 of this recognition apparatus, a light path adjustment plate 91 is disposed in lieu of the diffusion plate of FIG. 12, and the half mirror and the second light source are not disposed. Other configurations are almost the same as the thing of FIG. 12, and therefore, identical reference numerals and signs are given to identical constituent elements, and thereby, its explanation is omitted.
The light path adjustment plate 91 refracts light, which the first light source 79 emitted, with different angles, by a small area which was divided into a plurality of pieces in a manner of concentric-strips, and condenses it to a predetermined area where the object 10 to be detected is located. Then, by irradiating light with a plurality of different irradiation angles to the object 10 to be detected, it is configured so as to carry out illumination which is suitable for a surface state of the object 10 to be detected.
In addition, although it is not shown in the figure, the above-described JP-A-11-249020 publication discloses an illumination apparatus which was configured in such a manner that a number of light sources are disposed concentrically, and it is configured so as to be able to adjust an amount of light of the light source with respect to each circumference as a unit, depending on a surface state of an object to be detected, and thereby, it was configured to irradiate illumination light which was suitable for recognition of the object to be detected.
In the meantime, in recent years, such a circuit substrate that gold plating was applied to a substrate mark has increased, and it becomes hard for reflected light from the substrate mark to be incident to an image pickup camera, depending on a style of illuminating, and there was such a case that an image with high contrast is not obtained, and a recognition error occurs.
As to this point, in the illumination apparatus 70 shown in FIG. 12, illumination light along an optic axis of the image pickup camera 75 is applied to the object 10 to be detected, by the half mirror 76, and therefore, it is possible to sure capture reflected light from the object 10 to be detected, by the image pickup camera, and it is possible to obtain an image with high contrast. Therefore, it is possible to solve the above-described problem that a recognition error occurs. However, the half mirror 76 is disposed, and the second light source 85 is allocated on an outside the case 71 through the lens 74, and therefore, there were such problems that a configuration is complex and it is costly, and in addition, an apparatus grows in size and an installation space becomes large.
In addition, in the illumination apparatus 90 shown in FIG. 13, it is possible to sufficiently secure an amount of light which is applied to the object 10 to be detected and its vicinity, but it is not possible to surely solve the problem that it becomes hard for reflected light from the substrate mark to be incident to the image pickup camera, since the object to be detected is irradiated with light from a lateral direction.
In the same manner, the illumination apparatus, which was described in JP-A-11-249020 publication and in which a number of light sources are disposed concentrically and it was configured so as to be able to adjust an amount of light of that light source with respect to each light source group which exists on an identical circumference, can irradiate an object area with illumination light which is optimum on recognizing the object to be detected, but illuminates the object to be detected, with light from a lateral direction, and therefore, can not surely solve the problem that it becomes hard for reflected light from the substrate mark to be incident to the image pickup camera.
The invention aims to provide, in consideration of the above-described circumstance, an illumination apparatus which, even if an object to be detected is of a mirror surface shape and of a concavity and convexity shape, can carry out appropriate illumination which corresponded to it, over trying to realize low cost and miniaturization with a simple configuration, and accordingly enables to recognize an object to be detected without an error, and a recognition apparatus and a component mounting apparatus which were equipped with this.